Inks containing a water-dissipatable polyester or polyesteramide are well known in the art (see, for example, U.S. Pat. Nos. 4,704,309 and 4,738,785). Inks containing such a polymeric material have many desirable properties such as good adhesion to a variety of substrates and a wide viscosity range.
However, because of the wide range of printing conditions and substrates used in the printing industry, a given ink formulation can have ideal properties for some applications and poor properties for other applications. Block resistance, rub resistance, and reduced slide angle are properties that are highly desirable for many ink applications. It would be highly desirable to have inks containing water-dispersible polyesters or polyesteramides wherein these properties are improved.
Certain diacyl-glycerophospholipids such as lecithin are known to be useful as surfactants for some applications. We have surprisingly found that the addition of certain amounts of glycerophospholipids as hereinafter described, to certain aqueous inks containing a polyester material as hereinafter described, improves the block resistance, rub resistance, and slide angle properties of these inks.